1. Field of the Invention
The present invention relates generally to methods for forming multi-component oxide layers over substrates. More particularly, the present invention relates to chemical vapor deposition (CVD) methods for forming multi-component oxide layers over substrates.
2. Description of the Related Art
As technologies such as microelectronics fabrication technology and sensor element fabrication technology have advanced, there has evolved a continuing and accelerating interest in the use of multi-component oxide thin film layers within thin film fabrications such as but not limited to thin film microelectronics fabrications and thin film sensor element fabrications. Such multi-component oxide thin film layers are typically generally formed in such applications at thicknesses of less than about 20000 Angstroms, and more typically and more preferably at thicknesses of from about 50 to about 4000 Angstroms.
Multi-component oxide thin film layers are desirable in the aforementioned thin film microelectronics fabrications and thin film sensor element fabrications since such thin film layers may be formed to simultaneously possess several unique properties, such as but not limited to unique dielectric properties, ferroelectric properties, piezoelectric properties and/or pyroelectric properties which are often desirable, and not otherwise readily obtainable. Of particular interest in advanced thin film microelectronics fabrications are perovskite multi-component oxide thin film layers, such as but not limited to barium strontium titanate (BST) layers and lead zirconium titanate (PZT) layers, since such perovskite multi-component oxide thin film layers possess enhanced dielectric properties appropriate for use within high areal capacitance capacitors for advanced thin film microelectronics fabrications such as but not limited to advanced dynamic random access memory (DRAM) integrated circuit thin film microelectronics fabrications.
Of the methods for forming multi-component oxide thin film layers, such as perovskite oxide thin film layers, for thin film fabrications such as thin film microelectronics fabrications and thin film sensor element fabrications, chemical vapor deposition (CVD) methods and related epitaxial deposition methods, such as but not limited to atomic layer epitaxial (ALE) deposition methods, are in turn also presently of substantial interest. Additional variations upon chemical vapor deposition (CVD) methods and epitaxial deposition methods for forming multi-component oxide thin film layers within thin film fabrications such as thin film microelectronics fabrications and thin film sensor element fabrications include but are not limited to: (1) digital methods (which for the purposes of this application are defined as deposition methods where each reactant source material introduced into a reactor chamber within the deposition method is pulsed when forming a multi-component oxide thin film layer and at least one of the reactant source materials is pulsed without overlapping the pulses of the other reactant source materials); and (2) pulsed methods (which for the purposes of this application are defined as deposition methods where at least one reactant source material is introduced continuously into a reactor chamber within the deposition method employed in forming a multi-component oxide thin film layer while at least one other reactant source material is pulsed when introduced into the reactor chamber). Chemical vapor deposition (CVD) methods and related epitaxial deposition methods are of substantial interest when forming multi-component oxide thin film layers in such thin film applications due to: (1) the potential of those deposition methods for forming conformal multi-component oxide thin film layers with relative ease in comparison with alternative thin film deposition methods; and (2) the possibility of ready adaptation of chemical vapor deposition (CVD) methods and epitaxial deposition methods to continuous manufacturing processes.
While chemical vapor deposition (CVD) methods and related epitaxial deposition methods are thus desirable in the aforementioned thin film applications, chemical vapor deposition (CVD) methods and related epitaxial deposition methods are nonetheless not entirely without problems when forming multi-component oxide thin film layers in such applications. In particular, multi-component oxide thin film layers when formed within thin film microelectronics fabrications and thin film sensor element fabrications through chemical vapor deposition (CVD) methods and related epitaxial deposition methods often suffer from deficiencies including but not limited to: (1) compromised multi-component oxide thin film layer properties often related to attenuated multi-component oxide thin film layer crystallinity; (2) comparatively high deposition temperatures needed to form a multi-component oxide thin film layer with optimal properties; (3) attenuated precursor reactant source material incorporation efficiency within a multi-component oxide thin film layer; (4) significant reactant source material gas phase reactions when forming a multi-component oxide thin film layer; and/or (5) significant deposition reactor hardware costs associated with individually introducing individual reactant source materials into a deposition reactor chamber employed in forming a multi-component oxide thin film layer.
The present invention is therefore directed towards the goal of forming multi-component oxide thin film layers within fabrications such as but not limited to thin film microelectronics fabrications and thin film sensor element fabrications through chemical vapor deposition (CVD) methods and related epitaxial deposition methods, while avoiding the foregoing deficiencies.
Various oxide thin film layer deposition methods and materials have been disclosed within the art of oxide thin film layer deposition.
For example, Suntola et al., in U.S. Pat. No. 4,058,430 (Suntola I), and Suntola et al., in U.S. Pat. No. 4,413,022 (Suntola H), disclose various aspects of an atomic layer epitaxy (ALE) method which may be employed in forming simple (ie: single component) oxide thin film layers which may be employed within thin film microelectronics fabrications.
In addition: (1) Duray et al., in "Pulsed Organometallic Beam Epitaxy of Complex Oxide Films," Appl. Phys. Lett., Vol. 59 (12), Sept. 16, 1991, pp. 1503-05; (2) Hirai et al., in "Preparation of Tetragonal Perovskite Single Phase PbTiO.sub.3 Film Using an Improved Metal-Organic Chemical Vapor Deposition Method Alternately Introducing Pb and Ti Precursors," Jpn. J. Appl. Phys., Vol. 32 (Pt.1, No. 9B), September 1993, pp. 4078-81 (Hirai I); (3) Xie et al., in "Epitaxial LiTaO.sub.3 Thin Film by Pulsed Metalorganic Chemical Vapor Deposition From a Single Precursor," Appl. Phys. Lett., Vol. 63 (23) Dec. 6, 1993, pp. 3146-48; (4) Sotome et al., in "c-Axis-Oriented Pb(Zr, Ti)O.sub.3 Thin Films Prepared by Digital Metalorganic Chemical Vapor Deposition Method," Jpn. J. Appl. Phys., Vol. 33 (Pt. 1, No. 7A), 1994, pp. 4066-69; (5) Hirai, in "Preparation of Perovskite Oriented PbZr.sub.x Ti.sub.1-x O.sub.3 Films With Suppressed Vapor Phase Reactions by a Digital Chemical Vapor Deposition Method," Jpn. J. Appl. Phys., Vol. 34 (Pt. 1, No. 2A), February. 1995, pp. 539-43; and (6) Buchholz et al., in "In-plane Orientation Control of (001) YBa.sub.2 Cu.sub.3 O.sub.7- Grown on (001) MgO by Pulsed Organometallic Beam Epitaxy," Appl. Phys. Lett., Vol. 68 (21), May 20, 1996, pp. 3037-39 (Hiral II), each disclose one of various pulsed or digital chemical vapor deposition (CVD) methods or epitaxial methods for forming multi-component oxide thin film layers which may be employed within thin film microelectronics fabrications or thin film sensor element fabrications.
Similarly: (1) McMillan et al., in U.S. Pat. No. 5,138,520; (2) Eres et al., in U.S. Pat. No. 5,164,040 (Eres I); (3) Eres et al., in U.S. Pat. No. 5,330,610 (Eres II); (4) Kelly, in U.S. Pat. No. 5,366,555; and (5) Versteeg et al., in U.S. Pat. No. 5,451,260 are each directed at least in part towards various apparatus configurations, along with associated chemical vapor deposition (CVD) methods and epitaxial deposition methods, which may be employed in forming oxide thin film layers within thin film microelectronics fabrications and thin film sensor element fabrications. Disclosed are: (1) a pulsed heating and irradiation apparatus and method (McMillan et al.); (2) a pulsed supersonic jet apparatus and method (Eres I); (3) an externally controlled closed-loop feedback apparatus and method (Eres II); (4) a segregated reaction region single chamber reactor apparatus and method (Kelly); and (5) an ultrasonic atomization liquid delivery apparatus and method (Versteeg et al.).
Finally, there is disclosed by Graf et al. In U.S. Pat. No. 5,439,876 and Bednorz et al., in U.S. Pat. No. 5,648,321 correlated atomic layer epitaxy (ALE) methods which may be employed for forming within thin film microelectronics fabrications lattice structured layers of materials which may include, but are not limited to, high critical temperature (Tc) thin film superconducting materials.
Desirable in the art of thin film fabrication are additional chemical vapor deposition (CVD) methods and related epitaxial deposition methods by which thin film fabrications such as but not limited to thin film microelectronics fabrications and thin film sensor element fabrications may have formed therein multi-component oxide thin film layers, where the methods are employed to form the multi-component oxide thin film layers with: (1) improved multi-component oxide thin film layer properties due to enhanced multi-component oxide thin film layer crystallinity; (2) improved multi-component oxide thin film layer properties, such as but not limited to uniformity and conformality (where for the purposes of this application conformality is defined as uniformity upon a structured surface) at comparatively lower chemical vapor deposition (CVD) substrate temperatures; (3) enhanced precursor reactant source material incorporation efficiency within the multi-component oxide thin film layers; (4) attenuated reactant source material gas phase reactions when forming the multi-component oxide thin film layers; and/or (5) reduced chemical vapor deposition (CVD) reactor hardware costs associated with individually introducing individual reactant source materials within chemical vapor deposition (CVD) reactor chambers within which are formed multi-component oxide thin film layers. It is towards the foregoing objects that the present invention is directed.